----- Original Message -----
From: "Eric Swanson" <[EMAIL PROTECTED]>
To: "globalchange" <[email protected]>
Sent: Friday, September 22, 2006 5:15 PM
Subject: [Global Change: 711] Re: ESA scientists shocked
>
> hank - NOTE, do NOT email me items moderators reject! wrote:
>> I don't understand the last quote in that linked article, can someone
>> explain it?
>>
>> "... "As autumn freeze-up begins, the current pattern will undoubtedly
>> precondition the ice situation in the Central Arctic for the subsequent
>> ice season," Drinkwater said."
>
> Could this imply that next year's melt season will exhibit more of the
> same spectacular changes? If so, could we see a sudden disintegration
> of the sea-ice in this area, some what analogous to the Larson ice
> shelf breakup along the Antarctic Peninsula? Such an occurrence might
> send a large pulse of low salinity water into the North Atlantic Sub
> Polar Gyre. Oh, fun!
I had a think about that question, but didn't come to firm conclusion.
My first thoughts were as follows. The reason the ice was broken up
by the wind was because it was thinner. Now that it was broken up,
over that area it was on average thinner still because some places had
zero ice. Each year the perennial ice is thinning by 0.1 m [Rothrock,
et al., 1999] Therefore next year, since that ice will be 0.1 m thinner
than it is now, it will melt with the seasonal ice, and we will have open
water all the way to the pole, although there will be perennial ice
elsewhere in the Arctic Ocean.
If that was what Drinkwater thought why did he not say it? Perhaps
he was thinking that with a wet surface where the bracken perennial ice
is now, then the seasonal ice will grow out from it more slowly. If the
distance retreated by the summer ice is constant, and if the winter
advance is less then the ice edge will end up closer to the pole next
summer.
But the ice does not retreat a fixed distance. It is highly variable
depending on latitude. This could be due to the thickness of the
ice which in turn would vary with the salinity of the se water. Fresher
water in winter would lead to thicker ice. Hence areas where there is
abnormally high summer melting one year would lead to abnormally
melting the following year. If this is the case, then perhaps Drinkwater
meant that next year the ice in this sector would be thicker. Oh, fun!
Cheers, Alastair.
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